Topics: Muscle, Muscle contraction, Myosin / Pages: 3 (662 words) / Published: Apr 9th, 2013

Different types of muscle contractions:
Isometric- muscle contraction without a change in the length of muscle
Concentric- Muscle applies force as it shortens (lifting)
Eccentric- Muscle applies force as it lengthens (lowering)

Difference between type 1 and type 2 muscle fibers * Slow-twitch fibers * Type-I fibers * Fatigue resistant * Contract slowly and with relatively little force * Rely primarily on oxidative energy system * Fast-twitch fibers * Type-II fibers * Fatigue more quickly than slow-twitch fibers * Contract rapidly and forcefully * Rely more on anaerobic systems

Sliding Filament theory 1. ATP binds to myosin (45°). This causes an affinity change, and myosin is released from actin. 2. ATP ADP + Pi and myosin heads are cocked to 90° 3. Myosin heads bind to actin to form a cross-bridge 4. Pi released, and myosin springs back to 45°. Actin is pulled over myosin and toward the center of the sarcomere. This causes shortening of the sarcomere and is referred to as the “power stroke” 5. ADP is released, but myosin remains bound to actin (rigor state) until more ATP comes in and the cycle continues.

Actin- thin filament
Myosin-thick filament
Motor unit- a motor neuron and all the muscle fibers it innervates.

Layers of muscle tissue:
Muscle, fascicle, muscle fiber, myofibril

* Muscle Spindles * Respond to stretching of muscles * Results in contraction of agonist and relaxation of antagonist * Golgi Tendon Organs * Respond to changes in tension within tendons * Results in contraction of the antagonist and relaxation of the agonist

Flexibility: * The ability of a joint to move through its full range of motion (ROM) * Stretch- move joint beyond accustom ROM * Important for general fitness and wellness

* Joint structure—joints vary in direction and range of movement * Joint capsules =

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